For metal or non-metal pipeline, acoustic pulse technology can be used for rapid leak detection. the leakage tubes can be timely found in the process of overhaul, so as to improve reliability and economy of units.

2.Testing plans

Connect sound pulse instrument and tested pipes, when tube wall perforation, cracks or district extension are found by instrument, scan line of screen appears the sine angle fluctuation from left to right and from down to up (namely waveform phase angle begins with a negative value). When the tube wall concave or plugs like dirt, rusty spot in tube are found by instruments, the screen appears sine angular fluctuation from up to down (namely waveform phase angle begins with positive value). The severity degrees of penetrating defect or jam is proportional to the amplitude of waveform signals, the location of defects can be determined by scanning calibration.

Fig 1. test schematic diagram

Fig 2. test signal diagram

3.Detection technology and characteristics

Sound pulse detection is that when a bunch of acoustic wave spreads along a pipe, if it meets any opening, hole, ballooning, sag, crack, internal corrosion and deposition in pipes, a reflected wave will be sent back transmit end. Due to spreading speed of acoustic wave is fixed, through processing of computer system, the specific location of pipe anomalies can be determined accurately. Compared with other detection methods, sound pulse detection method has the following advantages:

· The fast leak detection of pipeline in service (more than 500 tubes per hour can be checked)